This invention relates to an oil-pump drive for an internal-combustion engine and a method of making an oil-pump drive for an internal combustion engine, in particular for a motorcycle.
It is known from the prior art to ensure the oil supply in an internal-combustion engine by means of gear pumps (see e.g. EP 0 451 684 A1) or internally-geared rotor pumps. It is also known to drive such oil pumps indirectly via the crankshaft using a chain or gear transmission. However, these arrangements are expensive because they require corresponding transmission members, require additional installation space, and play an important role in noise generation. Furthermore, internally-geared rotor-pump arrangements are known in which the inner rotor is pressed onto the crankshaft and is mounted in the oil-pump housing together with the outer rotor.
The present invention provides an improved motorcycle engine having a crankshaft, an oil pump coupled for rotation with the crankshaft, and a primary gear positioned between the oil pump and the crankshaft. Because the rotor of the oil pump is driven directly by a shaft via the crankshaft, additional drive components such as chains, gears and the like can be dispensed with.
In one embodiment of the present invention, a particularly simple and inexpensive connection of the oil-pump rotor to the crankshaft can be achieved if a gear arranged on the crankshaft collar has a central opening into which the shaft of the oil pump is inserted in a rotationally fixed manner. A simple positive connection between the gear and the rotor shaft can be achieved if the inserted end of the shaft and the opening in the gear are square. In alternative embodiments of the present invention, this same positive connection can be achieved by inserting a shaft having any other shape that can transmit torque into a similarly shaped opening in the primary gear.
In the first preferred embodiment of the present invention, the gear arranged on the crankshaft collar is advantageously fixed thereto by fasteners (for example bolts, screws, pins, and the like) arranged radially around the central opening, the gear simultaneously being usable as a drive for an intermediate shaft and a coupling. However, in a second preferred embodiment, the primary gear is integral with the crankshaft collar, thus eliminating the need for fasteners.
The oil pump is advantageously formed as an internally-geared rotor pump in which the inner rotor is driven by the shaft inserted into the gear of the crankshaft. Further advantageous embodiments and improvements of the oil-pump drive according to the invention for an internal-combustion engine are described below.